Using active thermography for defects inspection of flip chip

•Defects detection using active thermography is proposed.•Temperature distribution is acquired by the infrared imager.•The results in thermograph between defects and reference are very different.•The results in temperature history between them are very different.•Different kinds of chips with different sizes are tested.

With the development of electronics towards smaller, more compact, and increasingly complex, flip chip technology has been used extensively in microelectronic packaging, and disadvantages occur in traditional detection methods. It is indispensable to explore new methods for flip chip solder joint inspection. In this paper we investigate an approach for solder joint inspection based on the active thermography. The basic principle of the active thermography method is described, and the experimental investigation is carried out using the method. The test flip chip is heated by a non-contact heating source. The thermal distribution on two kinds of chips is captured by an infrared thermal imager. With median filter and segmentation processes, positions of the bumps are segmented. For chips with smaller bumps, principal component thermography is introduced to enhance the segmentation process. The analysis results demonstrate that missing bumps in flip chips can be discerned obviously, which proves the feasibility of the proposed method for defects inspection of flip chips.